Thanks Indian22!
I thought about it too when if it were a two stroke, there could be a pressure relief valve, but no rocker, as those are for intake exhaust. The exhaust valve may have on this one just been held open as pressure relief as I heard said out the exhaust.
Visually the ports of two stroke engines are not atop the cylinder but sort of midway also.
The only time I heard of no sump oil in a 4 stroke, was some guys video that he put together two Briggs and Stratton engines with 1 head in the center. The two compression strokes had the two pistons make twice the compression. And believe it or not, they guy I guess for some reason did not figure the oil bath and for a short while ran with grease smeared inside the crankcase for short maybe 3 minute run time and shut it down after that. Strange?